1. Field of the Invention
This invention relates to terminal group blocked hydroxyalkyl polyethylene glycol ethers used as foam inhibitors in detergent compositions.
2. Statement of the Related Art
Aqueous industrial detergents used for cleaning metal, glass, ceramic and plastic surfaces, generally contain additives to counteract undesirable foaming. Foam is formed when using such detergents, by impurities which detach from the cleaned substrate and accumulate in the cleaning bath. Additionally, using foam inhibitors may be necessitated by the detergent compositions themselves, which may contain anionic or nonionic surfactants that foam under certain working conditions or temperatures.
Adducts of alkylene oxides with organic compounds containing--preferably several--reactive hydrogen atoms in the molecule have long been used successfully as foam inhibitive additives. Adducts that have proven to be particularly effective include: propylene oxide with aliphatic polyols (see U.S. Pat. No. 3,491,029 and corresponding German Application No. 12 80 455, as well as British Pat. No. 1,172,135 and corresponding German Application No. 16 21 592); propylene oxide with aliphatic polyamines (see U.S. Pat. Nos. 3,463,737, 3,491,029 and corresponding German Application No. 12 89 597, as well as British Pat. No. 1,172,134 and corresponding German Application No. 16 21 593); and ethylene oxide and propylene oxide with aliphatic diamines, particularly ethylene diamine (see U.S. Pat. No. 3,696,057 and corresponding German Application No. 19 44 569). In addition to a favorable foam-inhibitive effect, alkylene oxide adducts such as the foregoing also exhibit the stability to alkalis generally required for use in commercial and industrial detergents. However, the foregoing compounds are not sufficiently biodegradable to satisfy the current legislative requirements in Germany and in many other countries.